Method of making bore holes



Feb. 21, 1933;

C. J. G. AARTS ET AL 1,898,926 METHOD OF MAKING BORE HOLES Filed Dec.19, 1931 FIG :4

fry veni'arJz I afiszs m, $3 614 Al 412w 4d;

If!" r I Patented Feb.v 21, 1933 UNITED STATES PATENT OFFICE OHRISTIANUSJOSEPHUS GODEIRIDUB .AABTB, OF VOORBURG, AND JOKANNEB ANTONIUS ALPHONSUSMEKEL, OB DELFT, NETHERLANDS; SAID AAR'IB ASSIGNOB .TO FBAN'CISCUSCOBNELIS BAARS,

OI ROTTERDAM, NETHERLANDS METHOD MARIN G BORE HOLES Application fledDecember 19, 1981, Serial No. 582,144, and in the Netherlands February2, 1981.

The invention relates to a method of making bore holes.

An object of the present invention is to provide methods of thermallyboring into the earth and apparatus suitable for use in carr ing themethod into effect.

The present invention is based on an entirely new principle, i. e., theaction of causing the ground, in which the bore hole is to be made, tomelt or at least to become plastic. This molten or plastic material isthen removed in this condition from the bore hole.

The molten material resulting from the boring operation most frequentlyossesses a density far reater than that 0 the rock constituting t eground, this latter being in the majority of cases, very porous, a tactwhich applies particularly to most sedimentary strata. When the rocknear the bottom of the bore hole is caused to melt and is simultaneouslysubjected to pressure (which must be en erior to the pressure in thestrata surroun ing the bore hole) there will be formed, at the moment ofthe contraction caused by fusion, a certain s ace which constitutes thebore hole, whilst t e molten material is comressed at the bottom andejected laterally eing eventually forced into the cracks and holespresent in the surrounding rock.

In this way a rin of molten gangue is formed this ring bemg forcedagainst the 7 rock in its original state by the pressure prevailing inthe hole. If there is no material removed upwards out of the bore hole,the diii'erence in volume between the molten and the'non-molten rock isthe sole cause of the formation of the hole. It the rock, owing to theaction of the internal source of heat at the bottom of the bore hole,acquires a certain viscosity, this is ordinarily sufiicient forattaining the required result.

The internal source of heat at the bottom of the hole may be obtained indifi'erent ways. An electric arc may, for example, be struck between anelectrode suspended in the base of the hole and the bottom of thelatter. The rock at the bottonr of the hole melts or becomes viscous,and owing to the high pressure prevailing in the hole as well as thecon- 50 traction produced at the moment of fusion,

the viscous mass is forced against the rock.

The rate of formation of the hole depends,

therefore, on the rate at which the heat penetrates into the rock. Thislatter rate is promoted by the ohmic resistance ofiered to the currentby the incompletely molten or nonmolten rock situated a short distancebelow the bore hole.

In those cases in which this ohmic resistance is too great for aspecific rock and would consequently necessitate the application ofexcessively igh voltages, the electric arc can be struck at the bottomof the hole between two electrodes and, if necessary, beblown towardsthe bottom of the hole by the action of a magnetic field, or may strikefrom both electrodes to a molten slag at the bottom of the hole.

The heating can also be effected by an electric resistance such as atungsten filament.

In all these cases the lateral ejection of the molten or plastic masscan be further facilitated by dlrecting a vigorous current of gas on tothe middle of the bottom of the bore hole, the molten material beingthereby laterally ejected.

It is also possible to reduce the source of heat at the base of theiiore hole by directing, for example, a gas flame on to the bottom ofthe hole. The admission of the gas and the air or oxygen must in thiscase be effected under'a pressure greater than the normal workingpressure prevailing in the hole. According to the two last indicatedmethods, the rate at which the hole is formed is determined by the rateat which the heat penetrates by conduction, into the rock. Whenemploying the first method, this conduction of heat is further romotedby the ohrlriic resistance offered to the current by the rec In caseswhere the rock surrounding the hole does not possess suificientconductivity this can nevertheless be overcome by exciting a highfrequency alternating electromagnetic field in the bottom of the hole,for example with the aid of a high frequency alternating current. Themolten rock at the bottom of the hole is first strongly heated andthereby becomes the seat of closed Fouin in a cold hole (and thereforewith insu cient electrical conductivity in the rock a metallicconducting cushion is first forms in the bottom of the hole by causingpieces of metal to-fuse together, for example pieces of iron which canbe introduced into the hole from a ove.

It is necessar to cool the 0011 which conducts the high equencyalternating current,

which cooling may be efiected by employing tubular conductors for thecurrent and circulating cooling water therethroug'h.

It is obvious that all substances ca able of favourably influencing thefusion an formation of the bore hole can in general be introduced intothe bore hole from above, in which case these substances can be selectedin accordance with the composition of the rock to be bored, so thatchemical influences can contribute at the same time as the thermalinfluences to the formation of the bore hole.

In general any means of heatin capable of co-operating in the formation0 the bore hple, according to the invention, may be em- P he molten rockitself constitutes the material for the formation of the walls of thebore hole.

The pressure prevailing in the inside of the bore hole is alwaysmaintained higher than the hydrostatic pressure exerted in the rock onthe exterior of the bore hole. This ressure can be regulated from aboveby the introduction or by the escape of the gas under pressure. In thosecases where these gases-or vapours are produced in the hole itself, themay be allowed to esca e through a valve. e formation of the ole can.always be efi'ected under a pressure higher than the highest ressure towhich the hole would be exposed uring its subsequent use.

Most rocks which have to be drilled are, inpractice, sufiicientlyorousin themselves in order to render possi Ie the formation of quickly, thewhole or a part ofthe molten the hole, accordin to the processhereinbefore described. I it is necessary to drill a rock which isnon-porous or insufficiently porous, or if it is desired to drill morematerial willhave to be removed from above. When drilling a non-porousrock it is not necessary to exert a pressure in the hole, because insuch a case it is impossible to eject the molten matter laterally intothe surrounding rock and on the other hand the hole in such a rockpossesses sufiicient resistance.

The method to be ado ted in this case for removing the molten roc fromthe hole depends on the nature of the rock. A portion will eva orate andescape from the top of the hole in t e form of vapour or will becomedeposited during its passage upwards in the is closed, for example, by aform of an easily removable" powder on the air from above in the hole,as a result of which 7 a large quantity will be vaporized and swegt sawa This current of gas directed towar the ottom of the hole can also bereinforced in such a way that mechanical pulverization is effected aswell as evaporation, it being possible sometimes to facilitate theformer, articularly by sudden cooling of the mo ten rock which causesthe latter to chip, by the.

introduction, from 'time to time, of a little water together with the'gas.-

The molten rock may also be removed by mechamcal means, for example bylowering into the bore hole an evacuated iron tube. This tube is of acone-like shape and has a special conical base in which an iron ball isdisposed, which, after the filling of the tube, can'function as a, stopvalve during its ascent. At the bottom of this conical iron receptacle asuction pipe is disposed, the base of which (In place of had any othersu ciently fusible material may also be used). 0n plunging the base ofthis suction pi e into the molten rock at the bottom of the ole, thelead plugwill melt and in consequence of the tube being evacuated themolten rock will be drawn up.

When the tube is raisedthe iron ball will function if necessary as astop-valve.

This oran analogous procedure can be adopted when it is necessary todrill a nonrous rock. The method of the invention is especially adaptedto borings in thepetroleum industry. The geological construction of theterrain to be bored is already known. During the borinighe' presence 0oil or water strata can both ascertained by slowly diminishing thepressure prevailing in the hole. The presence of oil or water willconsequently cause the lower molten partpf the hole to bend back inwardsand the vapours and gases which escape in the hole can be controlledfrom above. After having examined the material brought to light thepressure isaga'in raised so that the liquid which may have entered thehole is ejected, after which the process of fusion can be continued.

In this way it will thus be possible to bore consecutively throughdifferent oil strata. After the bore hole has been completed, it will bepossible to exploit at will all the strata at the same time orconsecutively by perforating the side wall of the bore hole 'at the lugof lead.

Ill);

the form of the electrode or coil used for the high frequencyalternating current or other heating means and on the admission of heat,also on the porosity of the rock and whether there is more or lessmaterial removed upwards out of the hole. The descent of an electrodecan be regulated and controlled from above. For example, the increase inthe distance between the electrode and the bottom of the hole, if theheating is accomplished by an arc struck between an electrode and thebottom of the hole, is accompanied, with the same voltage, by adiminution of the intensity of the current.

In cases where the arc is broken at the bottom of the hole, or if theoperation has to be restarted after an interruption, in a fairly coldhole, the arc can easily be restored, for example by letting a drop ofmercury fall into the hole. Since the sides of the molten rockthemselves function as the sides of the hole and since in consequence,iron piping will not be required, a direct current can be used equallyas well as an alternating current.

It is evident that it is in general simpler to use an alternatingcurrent, and, having regard to the above consideration, this kind ofcurrent will ordinarily be used. In certain cases a direct current maybe advantageous; and electrolytic phenomena may then be roduced whichcan be utilized for the elimination of the material of the hole (forexample in the form of vapour) in cases where it is necessary to drill,for example, a non-porous rock. In addition, it is evident that theatmosphere in the hole may, as desired, be rendered oxidizing orreducing.

it follows from the description hereinbefore given that the course ofthe boring can be exactly followed from above by manometer and ammeterreadings.

Some advantages of the new method of boring are as follows The bore holeis directed perpendicularly downwards. J

The diameter of the bore hole is approximately the same the whole of itslength; it is possible, for example, to construct a bore hole having adiameter of 20 to 30 centimetres and extending to an almost unlimiteddepth.

A very much greater depth can be obtained than by applying the hithertoknown methods. Owing to this it is possible to exploit supposed oilstrata at great depth and hitherto inaccessible. There is no danger,when applying the process in areas insufiiciently known from ageological point of view, of inadvertently drilling through a stratum ofoily sand without noticing it, such as has been the case hitherto, or ofblocking an oil stratum on applying the usual rinsing with the aid ofliquids and losing the latter from the operation. For a specific sourcethe quantity of oil raised may be much increased owing to thecircumstance that a considerable diameter can be realized even at agreat depth.

If necessary, the hole can be enlarged at the bottom by maintaining theheating means for a long time at the lowest leve An enlar ed chamber isthen formed at the bottom 0 the hole, into which, after the walls haveruptured, the oil can easily flow.

Not only is a better hole bored more rapidly and, if desired, to agreater depth and of greater diameter, but it is also much moreeconomic, owing to the fact that iron pi es are not required and that aconsiderably greater average speed of drilling is attained with the useof less personnel. In fact the construction of pipes, cementing andfishin jobs can be dispensed with.

%here are no losses of oil or gas and there is also no longer any dangerof fire when boring spouting sources since the bore hole is sealed tohigh pressure.

The invention will be explained with the aid of the accompanyingdiagrammatic drawing:

Figure 1 represents a method of operating where an electric arc isproduced between a lowered electrode and the bottom of the bore hole.

Figure 2 represents the bottom of a bore hole with a coil loweredinside, this coil being activated by a high frequency alternatlngcurrent.

Figure 3 shows a section of a bore hole where two electrodes areemployed for the formation of the arc.

Figure 4 represents an apparatus for raising the liquid material from abore hole.

In Figures 1' and 2, the solidified wall of the hole is represented byl, and 2 represents the liquid or plastic material surrounding the frontof the hole.

In Figure 1, 3 represents an electrode, which may be m the form of ahollow cylinder, and is cooled internally by the tubes 4. The electrodeis suspended by tubes through which a liquid circulates in the directionof the arrows. These tubes also convey the electric current. Between theelectrode 3 and the rock 2 an electric arc is struck which causes therock to melt or at least renders it plastic. The high pressureprevailing in the bore hole now forces the rock, which has becomeplastic, laterally outwards and downwards, this being rendered possibleby the contraction of the rock during fusion. Thehole is stopped by theplug 5, which hermetically seals the bore hole, even when very highpressures are used. The tubes 4 pass through this plug. The differentstrata are represented 1n the drawing by varied shading.

In Figure 2, 7 represents a coil with turns 8. A hi h frequencyalternating current, conveyed y the cable 9, is passed through .theseturns. The change. of 'ma etic field the heating is efl ected by meansof elecgenerates Foucault currents in t e rock 2, tric resistance, suchasatungsten filament. I which produce great heat which melts the Intestimony whereof, we afiix our signarock. n order to start the processsmall ture's.. 5 18065 f ir y b all w d to fall t the CHRISTIANUSJOSEPHIJS GODEFRIDUS AARTS. 70

ottom of the hole. Once slag is formed, the a .lounmss auromus mnousususxu. feed of-iron can be dis ensed with. 1 v

In Figure 3', 10 an 11 represent the electrodes between which anelectric arc is struck. 12 is a magnet giving rise to a magnetic 75field, which causes the electric arc-to deviate downwards so that thebottom of the bore hole is strongly heated.

Figurest represents an iron tube 13 provided with a tip 14 closed by aplug 15 of so readily fusible metal, and carrying at its upper end aball 16. The apparatus also" carries a stop cock 17, by means of .whichit can be evacuated, the apparatus being lowered into the'bore holeafter being evacuated. 85

The ti 14 is then plunged into the molten rock, t e plug 5 melts, theliquid mass mounts into the'empt tube and fills the'same. On raisin thetu 13 filled in the manner describe the ball 16 lprevents the materialpresent above the bal from escaping. In order to empty the molten massfrom the tube 13, the id '18 of the tube is unscrewed. -What we claim isr 95 1. A method of makin vertical bore holes of considerable depth in-te ground, comprising converting the material, in which the boring takesplace, into a non-solid condition by heating under a pressure superiorto the ressure in the strata surrounding the bore ole. 2. A method ofmaking vertical bore holes ofconsiderable depth in the ound com risingconverting the material, m which the a oring takes place, into anon-solid condition by heating and maintaining thematerial under apressure suflicient' to force it simultaneously downwards and sidewardsinto porous strata I surroundingthe bore hole. I no 3. A method of makinvertical bore holes of considerable depth in t e ound, compris ing.converting the material, in which the boring takes place, into a plasticor molten condition by heating under a pressure superior to 5 thepressure in the strata surrounding the bore hole and at least partlyremoving the plastic or molten material upwards out of the bore hole. 74. A method according to claim 1, wherein 120 the heating is efleotedwith the aid of an electric are between an electrode lowered into thehole and the bottom of the hole.

5. A method as claimed in claim 1, wherein the heating is efl'ected withthe aid of an elec-' 125 tric are between two electrodes lowered intothe bore hole, a magnetic field being applied between these electrodesto force the electric arc downwards. 6. A method as claimed in claim 1,wherein

